1. Carbon mineralisation and pore size classes in undisturbed soil cores
- Author
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Bouckaert, Liesbeth, Sleutel, Steven, Van Loo, Denis, Brabant, Loes, Cnudde, Veerle, Van Hoorebeke, Luc, and De Neve, Stefaan
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SPSS Inc. ,Computer software industry -- Analysis -- Study and teaching ,Toy industry -- Analysis -- Study and teaching ,Diagnostic equipment (Medical) -- Analysis -- Study and teaching ,Soil structure -- Analysis -- Study and teaching ,Agricultural industry ,Earth sciences - Abstract
Soil pore network effects on organic matter turnover have, until now, been studied indirectly because of lack of data on the 3D structure of the pore network. Application of X-ray computed tomography (X-ray CT) to quantify the distribution of pore neck size and related pore sizes from undisturbed soil cores, with simultaneous assessment of carbon (C) mineralisation, could establish a relationship between soil organic matter (SOM) decomposition and soil pore volumes. Eighteen miniature soil cores (diameter 1.2 cm, height 1.2 cm) covering a range of bulk densities were incubated at 20°C for 35 days. Respiration was modelled with a parallel first- and zero-order kinetic model. The cores were scanned at 9.44 µm resolution using an X-ray CT scanner developed in-house. Correlation analysis between the slow pool C mineralisation rate, [k.sub.s], and pore volume per pore neck class yielded significant (P < 0.05) positive correlations: r = 0.572, 0.598, and 0.516 for the 150-250, 250-350, and >350 µm pore neck classes, respectively. Because larger pores are most probably mainly air-filled, a positive relation with [k.sub.s] was ascribed to enhanced aeration of smaller pores surrounding large pores. The weak and insignificant relationship between the smallest pore neck class ( Additional keywords: first- and zero-order kinetic C mineralisation model, image analysis, pore size distribution, SOM decomposition, 3D soil pore structure., Introduction The spatial distribution of soil organisms is not random (Nunan et al. 2003; O'Donnell et al. 2007; Young et al. 2008): rather, their location in the soil matrix depends, [...]
- Published
- 2013
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